Automatic handling buffer for bare stocker

ABSTRACT

A buffer station for automatic material handling system can provide throughput improvement. Further, by storing to-be-accessed workpieces in the buffer stations of an equipment, the operation of the facility is not interrupted when the equipment is down. The buffer station can be incorporated in a stocker, such as bare wafer stocker.

FIELD OF THE INVENTION

The present invention relates to apparatuses and methods to store andtransfer objects, and more particularly to workpiece stockerconfigurations such as stocker for semiconductor wafers, reticles orcarrier boxes.

BACKGROUND

In the process of manufacturing semiconductor devices, LCD panels, andothers, there are hundreds of processing equipments and thus hundreds ofmanufacturing steps. It is very difficult for the flow of the wafers,flat panels, or LCDs (hereafter workpiece) to be uniform from step tostep, from tool to tool. Despite the best planners, there is always theunexpected scenario, such as a tool down, an emergency lot comingthrough, a periodic maintenance lasting longer than planned, thus thereare various accumulations of the workpieces at certain steps for certaintools. The accumulated workpieces will need to be stored in a storagestocker, waiting to be processed.

In a typical bare stocker system, a robot is typically used to removethe workpieces from the carrier boxes, and then loaded into a storagechamber, where the workpieces are stored without the original carrierboxes. For box stocker system, the workpieces are stored together withthe carrier boxes, without the need for removing them out of the carrierboxes.

The carrier box is a protective container to minimize the substrateexposure to the environment outside of the processing machines andprotect the substrate against particulate contamination. The carrierboxes are handled by an operator or by an automatic material handlingsystem such as automatically guided or overhead transport vehicles thattravel on predetermined routes, either on the ground or suspended onceiling tracks. For semiconductor wafers, the carrier boxes are normallycassettes pods, such as SMIF (standard machine interface) or FOUP (frontopening unified pod), which are handled by an operator at the toolsequipment front end module (EFEM) or automatically picked up and placedin the automatic transport system.

One type of conventional transport system is an overhead transport (OHT)system, which comprises an OHT vehicle, which runs freely on a railmounted on a ceiling. The OHT vehicle carries a cassette pod betweenfacility equipment, such as processing systems and stockers. The OHTvehicle can load or unload a cassette pod onto a load port of theequipment, for example a MLP (Mobile Launch Platform) or an EFEM. Fromthere, the cassette pod or the wafers can be transferred from or to theinside of the equipment.

SUMMARY

Methods and apparatuses for improved equipment are disclosed. Inexemplary embodiments, IO buffer for automatic material handling systemis provided for improving the throughput of equipment, especially forbare wafer stockers. With the fast access time of automatic carriertransport, and the slow response of stocker storing bare wafers, the IObuffer can improve the throughput of the bare wafer stocker bypre-assembling the wafer carriers.

In an exemplary embodiment, the IO buffer station stores the workpieceto be needed in containers. Thus when recalled, the workpiece will bebrought directly from the IO buffer station to the automatic carriertransport, instead of waiting for transferring to the container from thechamber. In an embodiment, the IO buffer operation is independent of thestocker, thus providing continuous flow of the facility even when thestocker is inoperative. Further, in exemplary embodiments, the inventioncomprises an algorithm or a controller for determining the sequence ofthe workpiece flow, for example, to anticipate or to know the workpiecesto be brought to the buffer station. In a facility, such as asemiconductor fabrication facility, the workpiece flow can be importedto the controller as an input.

The present invention further discloses a scalable stocker configurationfor storing workpieces in a fabrication facility, especially a waferstocker or a reticle stocker for semiconductor processing. In anexemplary embodiment, the workpieces are stored in 2D linear array ofshelves disposed on left and right walls of the storage area, togetherwith a center linear robot handling assembly. In this configuration, thestorage area can be extended toward the service area while keeping thesame clean room front surface. The stocker configuration can alsoprovide the storage of the workpieces in a highly dense configuration,in preferably vertical positions. The center linear robot includes acircumferential edge gripper handling assembly, approaching and pickingup the workpieces from the circumferential edges.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 shows an exemplary embodiment of the buffer and stocker accordingto the present invention.

FIG. 2 illustrate various preferred embodiments of the present bufferassembly. FIG. 2A illustrates a ceiling-based buffer assembly. FIG. 2Billustrates a floor-based buffer assembly. FIG. 2C illustrates a crossconfiguration where a ceiling-based buffer interfaces with a floor-basedtransport.

FIG. 3 illustrates another exemplary embodiment of the buffer assembly

FIG. 4 illustrate other exemplary embodiments of the buffer assembly.FIG. 4A illustrates two separate automatic transports, serviced by twobuffer loading stations through two transfer mechanisms. FIG. 4Billustrates two separate automatic transports at opposite ends. FIG. 4Cillustrates two buffer loading stations servicing the same automatictransport.

FIG. 5 illustrate exemplary embodiments of the present buffer assemblyhaving a top buffer transport and a bottom buffer transport. FIG. 5Aillustrates a mechanism to transfer containers between the top andbottom buffer loading stations. FIG. 5B illustrates an additionalstation to transfer container between the two buffer loading stations.

FIG. 6 illustrate the top view of various exemplary embodiments of thebuffer assembly interfacing an automatic transport. FIG. 6A illustratesa plurality of buffer stations arranged in one row facing the automatictransport. FIG. 6B illustrates additional buffer stations arranged in anopposite and parallel row, sandwiching the transfer mechanism. FIG. 6Cillustrates additional buffer loading stations interfacing the sametransport.

FIG. 7 illustrates a top view of an exemplary buffer assembly having onerow of buffer stations interfacing two automatic transports.

FIG. 8 illustrate top views of exemplary buffer assembly configurationswhere there are two transports, either intersecting each other or inparallel. FIG. 8A illustrates a buffer assembly configuration comprisingtwo buffer loading stations located at the end of the buffer stations,together with two intersecting transports. FIG. 8B illustrates a bufferassembly configuration comprising four buffer loading stations locatedat two ends of the buffer stations, together with two paralleltransports. FIG. 8C illustrates a buffer assembly configurationcomprising three buffer loading stations located at two ends of thebuffer stations, together with two intersecting transports.

FIG. 9 illustrates an exemplary buffer configuration with a linearrobotic mechanism to transfer the containers from the buffer stations tothe buffer loading stations.

FIG. 10 illustrates an exemplary configuration of the automatic bufferincorporated in the top section of the stocker.

FIG. 11A illustrates a top view of an exemplary stocker storage area.

FIG. 11B illustrates an exemplary extension of the scalable stocker.

FIG. 12 illustrates a top view of an exemplary stocker utilizing thescalable storage area.

FIG. 13 illustrates a cross section of an exemplary stocker utilizingthe scalable storage area.

FIGS. 14 and 15 show different views of an exemplary embodiment of acontainer.

FIG. 16 shows an exemplary robot handling arm according to the presentinvention.

DETAIL DESCRIPTIONS

The present invention, in general, pertains to methods and apparatusesfor an IO buffer assembly and a storage stocker system for a fabricationfacility. According to an embodiment, an IO buffer for automaticmaterial handling system is provided. The IO buffer can compensate forthe speed of the equipment or stocker, especially when interfacing withthe fast throughput of an automatic guidance system for wafercontainers. The IO buffer is preferably associated with a processequipment, a metrology equipment, or a stocker, such as a wafer stocker,to facilitate the transfer of the wafers. According to still anotherembodiment, stocker management, methodology and apparatus for IO bufferare provided.

To accommodate the requirement of high throughput, an IO buffer assemblyadjacent the IO loaders is included to store the ready carriers. Such IObuffers are generally configured adjacent the automatic materialhandling system, and include shelves for storing wafer carriers with atransport system for transferring the wafers carriers between the IObuffer and the automatic material handling system. In an aspect, the IObuffer comprises a 2D array of station, together with an XY linear guiderobotic for transfer operation, preferably located at the top or bottomfor automatic vehicle transport.

The IO buffer is preferably stored the containers to be needed next, andmore preferably stored an adequate number of containers for apredetermined period so that the operation of the fabrication facilityis not stopped or inconvenient during a general failure of theassociated equipment. In another embodiment, the present inventiondiscloses a storage system employing an IO buffer. The articles storedin the IO buffer are preferably stored in bare format, which needed tobe transferred to a container before transporting to the next equipment.

The IO buffer is preferably independent from the stocker, so that evenif the stocker experiences a failure, there are enough containers toservice the facility during the repair of the stocker. The storagesystem can communicate with the fabrication facility to know whatarticles to be needed, immediately and in the near future. Thus thestorage system can retrieve the articles from the storage area and storein the IO buffer. The communication equipment can be a controller or acomputer system, managing the information retrieval and sequencer forthe workpiece flow of a facility. The algorithm can determine theworkpieces to be stored in the buffer stations, waiting to be accessed.

Exemplary embodiments of the present invention include a buffer assemblyfor automatic handling system in connection with a stocker in afabrication facility such as semiconductor fabrication facility. In anaspect, the stocker stores substrates (such as wafers, LCDs, orreticles) in bare form, without a protective container. With the wafersstored in bare form, taking wafers in and out of the storage area wouldtake longer than the access time of the automatic handling system, thusin exemplary embodiments, the present invention discloses a bufferassembly for the automatic handling system to improve the throughput.

In an embodiment, the IO buffer can be an independent system, to bemounted adjacent a process, metrology or stocker tool to provideautomatic handling buffering for the tool. In another embodiment, the IObuffer system may be incorporated into a stocker capable of storingrelatively large numbers of wafers in a scalable footprint. While thedescription of the invention includes FOUP pods, other types ofcontainers can be used, for example, SMIF pods, pods of various sizes,bottom opening pods, front opening pods, cassetteless pods, and opencassettes. Additionally, the term substrate or wafer can mean workpieceother than semiconductor wafers, such as reticles, flat panel displays,and other substrates which may be stored and/or transported within podsand cassettes.

Exemplary embodiments of the present invention include a stockercomprising a storage area, which preferably storing bare wafers. Thestocker further comprises a stocker loading station to transfer wafersfrom a container to the storage area. The stocker also comprises anautomatic handling station, such as an OHT loading station, fortransferring the container to the OHT track. In an aspect, the stockerloading station can perform the function of the OHT loading station. Inanother aspect, there are a separate stocker loading station forinterfacing with the stocker, and an OHT loading station for interfacingwith OHT track. There can also be transfer mechanism for movingcontainers between the stocker loading station and the OHT loadingstation.

The present stocker can minimize the wait time by providing an OHTbuffer, which provides input and output OHT buffering capability, eitherservicing a ceiling-based conveyor or a floor-based conveyor. In oneembodiment, the stocker includes a ceiling-based OHT buffer adjacent theceiling-based conveyor. The OHT buffer may, for example, store multiplecontainers, allowing fast throughput to the OHT regardless of the speedof the stocker. In another embodiment, the ceiling-based OHT buffer canservice interbay and intrabay conveyor systems. In another embodiment,the buffer is located near the floor for interfacing with a floor-basedconveyor for moving containers out of the stocker's container storagearea and onto the facility floor-based conveyor. In another embodiment,the buffer is located near the ceiling for interfacing with aceiling-based conveyor to move containers in or out of the stocker'sstorage area. In one embodiment, the input-output buffer may storemultiple containers. The buffer is random access, thus supports thedelivery of different priority containers.

The present stocker is also described in conjunction with OHT tracks orconveyors, but may also operate with other automatic material transportsystems such as an overhead shuttle (OHS), a rail guided vehicle (RGV),an automated guided vehicle (AGV). For description purposes,“ceiling-based” means any height above the container loading height of aload port, and “floor-based” below the container loading height of aload port, including under the facility floor.

FIG. 1 illustrates an exemplary stocker according to the presentinvention. The stocker 10 comprises a storage area 17 for storingwafers, preferably in bare form. The storage area 17 typically comprisesshelves and compartments 17A for stacking wafers. The storage area 17also can comprise an inner robotic mechanism (not shown) for transferwafers in and out of the storage area.

The inner robotic mechanism can move vertically and horizontally toaccess walls of storage shelves positioned within the stocker (e.g., acontainer storage area). Such a robotic mechanism is well known in thesemiconductor industry and therefore, a further description of therobotic mechanism is not necessary. Generally, it would take some timefor the containers to be loaded or unloaded to the stocker storage, thusthe OHT buffer can reduce the waiting time at the conveyor, leading tohigh throughput.

Interfacing the storage area 17 is a loading station 13 for inputting oroutputting wafer containers, and a robotic transfer 15 for transferringwafers from the loading station 13 to the storage area 17. The loadingstation can comprise an EFEM station for handling wafer containers suchas FOUP or SMIF. The loading station can be handled by an operator, thusproviding manual handling of the wafer containers. In manual mode, thewafer containers can be carried by an operator, loading into the loadingstation 13 to receive wafers from the stocker storage area, or to placewafers from the containers to the storage area. The loading station cancomprise an automatic loading station, such as a MLP (Mobile LaunchPlatform), designed for accepting containers from an automatic handlingsystem, such as OHT track. The loading station can comprise a manualEFEM loading station and an OHT loading station, together with atransfer mechanism between these stations. In an aspect, the EFEMstation interfaces with the storage area, and the OHT loading stationinterfaces with the OHT track. After receiving the container from theOHT track, the transfer mechanism then transfers the container from theOHT loading station to the EFEM station, where the wafers can be loadedinto the storage area. In an embodiment, there is one OHT loadingstation (since automatic loading can be fast) and a plurality of EFEMloading stations (since manual loading can be slower). Both OHT loadingstation and EFEM loading station can receive containers from operator,where the OHT loading station can transfer the container to either theEFEM or the OHT station 11 to transfer to the OHT track, and the EFEMstation can transfer wafers to or from the storage area of the stocker,or to the OHT loading station.

In exemplary embodiments, the wafers are stored vertically in thestorage area, while being stored horizontally in the containers. Theexemplary stocker can comprise robotic mechanisms and loading stationsto accommodate the change in direction. For example, the robotictransfer 15 receives the wafers in horizontal direction from thecontainer in the loading station 13, and places the wafer into a dropstation (not shown) preferably within the storage area 17. The dropstation can be adapted for holding a substrate, which can be picked upfrom the bottom or from the edges. For example, a horizontal substratecan be handled from the bottom side by a robot end effector and droppedto the drop station. An edge gripping robot arm can pick up thesubstrate from the edge and then transfer the substrate to a storagecompartment in the vertical direction. Thus a drop station canaccommodate a change in storage direction of the substrate, for example,from horizontal to vertical, or vice versa.

An inner robotic mechanism (not shown) in the storage area 17 then picksup the wafer and stores in vertical direction in the storage area. Thewafers stored are also preferably stacked closely for higher storagecapacity.

The stocker further comprises a plurality of buffer stations 12 whichare interfacing with the automatic handling system such as the OHTvehicle and track 19. The buffer stations 12 are preferably connected toan OHT station 11 for receiving and placing container from and to theOHT track and vehicle 19. There can be multiple OHT tracks, thusexemplary embodiments of the present stocker comprise one or more of OHTstations to accommodate the OHT tracks. A transfer mechanism (not shown)transfers the container from or to the OHT track and vehicle 19 whenreaching the OHT station 11. A buffer transfer mechanism can transferthe container from the OHT station 11 to and from the buffer stations12. A transfer mechanism such as the MLP can also transfer the containerfrom the OHT station to the loading station 13, for transferring wafersto the storage area 17.

A buffer transfer mechanism moves a container between the bufferstations and the OHT station 19 or the buffer loading station 11. Abuffer transfer mechanism may comprise any mechanism that transfers acontainer. For example, any mechanism whereby the container is gripped,lifted, and moved. These movements may be accomplished by a single ormulti-segmented arm, or by a linear slide. In addition, a separatemechanism could be used to lift the container from underneath.

Each buffer transfer mechanism is preferably located at the I/O end ofthe input-output buffer for transferring a container on or off thebuffer stations. A buffer transfer mechanism can include feedbackcircuit such as sensors or position monitoring circuits. Anothertransfer mechanism can be used to transfer containers from the bufferloading station to the automatic transport. The transfer mechanism caninclude a director to rotate a container exiting the track or conveyor.

In exemplary embodiments, the storing sequence starts with the OHTvehicle carries a container on the OHT track to the OHT station 11. Thetransfer mechanism releases the container from the OHT vehicle andplaces the container onto the OHT station. If the stocker is busy, orotherwise not ready to receive the wafers, the container can be placedin the buffer area by the buffer transfer mechanism. When the stocker isready, the container can be put back onto the OHT station. A transfermechanism, such as the MLP and other transfer mechanism, transfers thecontainer to a loading station such as the EFEM. From the EFEM, thewafers are retrieved and stored in the storage area 17. In an aspect,there is an additional drop station in the stocker where the wafers aredropped to the drop station before entering the storage area. The dropstation can be used to change the direction of the wafer storage, forexample, receiving the wafer in horizontal direction and placing thewafer in vertical direction. The wafer is retrieved from the EFEM by atransfer robot, which then places the wafer in the drop station. Anotherinner robot retrieves the wafer from the drop station and stores thewafer in the storage location. In an embodiment, the transfer robot isdesigned to accommodate the wafer in the EFEM, which is typically arobot to retrieve wafer in horizontal direction. The inner robot isdesigned to accommodate the wafer in the storage area, which is storedin vertical direction. The drop station is designed to accommodate bothrobots, accessed by horizontal and vertical directions.

Sequence for retrieval wafers is reverse. The wafers are retrieved fromthe storage area and loaded into the FOUP waiting in the EFEM. Optionaldrop station can be used, for example, to change directionality of thewafers. There can be a pre-aligner for aligning the wafer, or the dropstation can act as an aligner. The FOUP container is transfer to the OHTstation, for example, by a transfer mechanism to move the container to aMLP, and then to the OHT station. If the OHT vehicle is ready, thecontainer can be transferred directly to the OHT track and moves to therequired equipment. If the OHT is not ready, or the stocker is lookingahead, the container is stored in the buffer by the buffer roboticmechanism. When the OHT is ready, the buffer robotic mechanism transfersthe container back to the OHT station to be loaded to the OHT vehicle.

The stocker can include a vertical module, such as a MLP fortransporting containers. After a container is placed on the verticalmodule, the container may be transferred to the EFEM, or be sent intothe OHT buffer loading station. From the OHT loading station, thecontainers can be sent to the automatic transport or to the bufferstations, one or more at a time in any order.

The buffer area can be located on top, bottom, left, right, front orback of the stocker. The buffer area can be a linear array distributedwithin one side surface of the stocker, such as the top side, the bottomside, the front side, the back side, the left side or the right side.The buffer array can be one layer or multiple layers. The number ofbuffer stations depends on the demand and the throughput of the stocker.If there is high demand for a slow throughput stocker, the number ofbuffer stations can be high to accommodate the situation.

In an aspect, the buffer area is located in the top area of the stocker.This location can accommodate the ceiling-based automatic handlingsystem such as OHT track. In another aspect, the buffer area is locatedin the bottom area of the stocker. This location can accommodate thefloor-based automatic handling system. In other aspects, the buffer areacan be located in other sides, though other optimizations might beneeded. For example, the front side might already be used for EFEM andmanual buffer, the back side might already be used for service door, theleft or right sides might increase the width of the stocker.

The stocker can include a ceiling-based I/O conveyor buffer dedicated toceiling-based conveyor transport. The ceiling-based I/O conveyor bufferis preferably located at the same height or elevation as the OHTconveyor. Locating the I/O conveyor buffer at substantially the sameheight as the conveyor can simplify the transfer of the containers. Thestocker may include a floor-based I/O conveyor buffer. Operation of thefloor-based I/O conveyor buffer is similar to that of the ceiling-basedI/O conveyor buffer.

The transfer assembly includes a mechanism, such as a lift or adisplacement assembly, for transferring a pod from the OHT system to abuffer station or a transport station (such as a MLP), or a load/unloadstation (such as an EFEM).

The buffer transfer mechanism can include an X movement mechanism and aY movement mechanism. Since each pod often has a standard configuration,for example, a semiconductor transport pod having a handle on top, therobot includes a robot arm adapted to engage the pod. The robot armengages the handle and transports the pod between an OHT buffer loadingstation, a buffer storage station, an OHT MLP station and an EFEMload/unload station. For example, the robot arm may be used to move atransport pod from a OHT system onto a OHT loader, from a OHT loader toa buffer storage location, from a buffer storage location to a OHT MLP,from a OHT MLP to a EFEM, and vice versa.

FIG. 2 illustrate various preferred embodiments of the present bufferassembly. The buffer assembly comprises a transport buffer whichincludes one or more buffer stations 101 for storing containers and abuffer loading station 104 adapted for holding a container. The bufferassembly also comprises a buffer transfer mechanism 202 to transfer acontainer between the buffer loading station 104 and the buffer station101. The buffer assembly further comprises an interface mechanism 204 or205 for transferring a container between a bare substrate stocker andthe transport buffer. For example, interface mechanism 204 can transfera container between the buffer loading station 104 and the stockerloading station 103, which is responsible for loading substrates to thestorage area 102 of the stocker through a transfer mechanism 201. Therecan be other stages between the stocker loading station 103 and thestorage area 102, for example, a drop station to change thedirectionality of the substrate before being stored in the storage area102. Alternatively, interface mechanism 205 can transfer a containerbetween the buffer stations 101 and the stocker loading station 103.Optionally, the buffer assembly comprises a mechanism 203 to transfercontainer from the buffer loading station 104 to the automatic transport105, such as an OHT track or conveyor.

FIG. 2A illustrates a ceiling-based buffer assembly where the bufferstation 101 is located on top of the stocker and the stocker storagearea 102. The buffer loading station 104 is preferably located in thevicinity of the buffer station 101 for ease of container transfer. FIG.2B illustrates a floor-based buffer assembly where the buffer station101 is located at the bottom of the stocker and the stocker storage area102, together with the buffer loading station 104. These configurationsare well suited for a ceiling-based or floor-based automatic transport105 and 105A, respectively, since the communication 203 can be short anddirect. Other configurations can be implemented, based on the particularsetup of the facility floor. For example, FIG. 2C illustrates a crossconfiguration where the ceiling-based buffer 101 interfaces with afloor-based transport 1-5A through mechanism 203A.

FIG. 3 illustrates another exemplary embodiment of the buffer assembly,comprising an additional station 106, interfacing the stocker such asthe stocker loading station 103 and the transport buffer, such as thebuffer loading station 104. The station 106 can be a MLP (mobile launchplatform), designed for transfer container to the automatic transport105. For example, an operator can load a container to the MLP, which isthen transferred to the buffer loading station 104 through the mechanism207. The mechanism 207 can be an elevator, elevating the container fromthe support platform of the MLP to the platform of the buffer loadingstation 104. From the loading station 104, the container can betransferred to the automatic transport 105 through mechanism 203. Thestation 106 can interface with the stocker loading station 103,preferably through a mechanism 206. For example, the stocker loadingstation 103 can be an EFEM, which is designed to interface with thestocker storage area 102.

FIG. 4 illustrate other exemplary embodiments of the buffer assembly,comprising an additional buffer loading station 104A with the samemechanism 202 interfacing with the buffer stations 101. The samemechanism 202 can service both buffer loading stations 104 and 104A asshown in these figures. Alternatively, a different transfer mechanismcan be implemented to service the addition buffer loading station 104A.The additional buffer loading station 104A can be linked to the sameautomatic transport 105 or to another automatic transport 105A through asame or different transfer mechanism 203A.

FIG. 4A illustrates two separate automatic transports 105 and 105A,serviced by two buffer loading stations 104 and 104A through twotransfer mechanisms 203 and 203A, respectively. The two automatictransports can be located at opposite ends of the buffer assembly, forexample, at the front and the back of the stocker. The two automatictransports can be located at two sides of the buffer assembly, forexample, at the front and the left (or right) side of the stocker. Asame transfer mechanism 202 can be used to service the two bufferloading stations 104 and 104A, transferring containers from the bufferstation 101 to the buffer loading stations 104 and 104A.

FIG. 4B also illustrates two separate automatic transports 105 and 105Aat opposite ends. For example, the transport 105 can be ceiling-basedtransport and the transport 105A can be floor-based transport. Thusmechanism 203 is shown transferring container at the same height, fromthe ceiling station 104 to the ceiling transport 105, and mechanism 203Ais shown transferring container at the different height, from theceiling station 104A to the floor transport 105A. Further, the mechanismtransferring container from buffer station 101 can be different, forexample, mechanism 202 to transfer to buffer loading station 104 andmechanism 202A to transfer to buffer loading station 104A.

FIG. 4C illustrates two buffer loading stations 104 and 104A servicingthe same automatic transport 105 with mechanisms 203 and 203Atransferring container from stations 104 and 104A, respectively, to thetransport 105. Same mechanism 202 can be used to transfer container frombuffer station 101 to the buffer loading stations 104 and 104A.

FIG. 5 illustrate exemplary embodiments of the present buffer assemblyhaving a top buffer transport and a bottom buffer transport. Thetop/bottom buffer transport comprises buffer station 101/101A withmechanism 202/202A interfacing buffer loading station 104/104, whichinterfaces automatic transport 105/105A through mechanism 203/203A.There are also mechanisms to transfer containers from the stocker to thebuffer assembly (not shown).

FIG. 5A illustrates a mechanism 208 to transfer containers between thetop and bottom buffer loading stations 104 and 104A. FIG. 5B illustratesan additional station 106 such as a MLP to transfer container betweenthe two buffer loading stations 104 and 104A, through mechanisms 207 and209, respectively. Mechanism 206 is also used to communicate with thestocker loading station 103.

FIG. 6 illustrate the top view of various exemplary embodiments of thebuffer assembly interfacing an automatic transport 105. FIG. 6Aillustrates a plurality of buffer stations 12 arranged in one row facingthe automatic transport 105. Transfer mechanism 210 can transfer anycontainer within the buffer stations 12 to the buffer loading station104, and then transfer from there to the transport 105 through themechanism 203. FIG. 6B illustrates additional buffer stations 12Aarranged in an opposite and parallel row, sandwiching the transfermechanism 210. The transfer mechanism 210 can service both bufferstations 12 and 12A, transferring containers to the buffer loadingstation 104. FIG. 6C illustrates additional buffer loading station 104Ahaving mechanism 203A interfacing the same transport 105. The samemechanism 210 can service the plurality of buffer stations 12 and 12Aand the plurality of buffer loading stations 104 and 104A.Alternatively, additional transfer mechanisms can be implemented forservicing different buffer stations and/or buffer loading stations.

These configurations can be for top area of stocker with ceiling-basedOHT track, or for bottom area of stocker with floor-based track. Theseconfigurations can also be used for front, back or left/right side withappropriate modifications. In FIG. 6C, the buffer assembly comprises tworows of buffer stations 12 and 12A, facing the clean room area, with amiddle row for transfer. With two row buffers, access to the bufferstations, meaning the movement of the container, can be in the sameheight level, thus the height of the buffer assembly can be about theheight of the container. Thus two row buffer assembly provides smallclean room area together with small height. An OHT track 105 provides anOHT vehicle running at the front (or back) of the stocker. The first twolocations in the buffer area can be OHT stations (or buffer loadingstation) 104, for interfacing with the OHT track. There can be two OHTstations 104 and 104A, providing twice the throughput from the OHTvehicle to the stocker. Alternatively, there can be only one OHT station104, with the other station 104A being a buffer station 12. The OHTvehicle carries a container along the OHT track 105, stops by the OHTstation 104/104A. A transfer mechanism 203/203A transfers the containerfrom the OHT vehicle to the OHT station 104/104A, respectively. From theOHT station 104/104A, the container can be transferred to the bufferstations 12/12A, or can be loaded to the loading station (MLP or EFEM)of the stocker (not shown).

The buffer stations can interface more than one automatic transport suchas OHT tracks. FIG. 7 illustrates a top view of an exemplary bufferassembly having one row of buffer stations 12 interfacing two automatictransports 105 and 105A. Same or different mechanism 210 can transfercontainers from any buffer station 12 to any buffer loading station 104or 104A. Separate mechanisms 203 and 203A are shown to transfercontainers from buffer loading station 104 and 104A to transports 105and 105A.

FIG. 8 illustrate top views of exemplary buffer assembly configurationswhere there are two transports, either intersecting each other or inparallel. Other configurations are also possible, such as more than twotransports. The buffer assembly comprises two rows 12 and 12A of bufferstations, arranged in parallel with a middle transfer mechanism. Thenumber of buffer loading stations can be different, for example, therecan be two, three or four buffer loading stations.

FIG. 8A illustrates a buffer assembly configuration comprising twobuffer loading stations 104 and 104A located at the end of the bufferstations, together with two intersecting transports 105 and 105A. Bufferloading station 104 comprises mechanism 203 to transfer container to thetransport 105. Buffer loading station 104A comprises mechanism 203A totransfer container to the transport 105, and mechanism 203B to transfercontainer to the transport 105A.

FIG. 8B illustrates a buffer assembly configuration comprising fourbuffer loading stations 104, 104A, 104B, and 104C located at two ends ofthe buffer stations, together with two parallel transports 105 and 105A.Each buffer loading station 104/104A/104B/104C comprises mechanism203/203A/203B/203C, respectively, to transfer container to the transport105/105A.

FIG. 8C illustrates a buffer assembly configuration comprising threebuffer loading stations 104, 104A, and 104B located at two ends of thebuffer stations, together with two intersecting transports 105 and 105A.Buffer loading station 104/104B comprises mechanism 203/203C to transfercontainer to the transport 105/105A, respectively. Buffer loadingstation 104A comprises mechanism 203A to transfer container to thetransport 105, and mechanism 203B to transfer container to the transport105A. A same mechanism can be used to service the buffer stations andthe buffer loading stations. The empty station at the end of the bufferrow can be used for buffer station.

FIG. 9 illustrates an exemplary buffer configuration with a linearrobotic mechanism to transfer the containers from the buffer stations 12to the buffer loading stations 104/104A. Two stationary parallel tracks45A and 45B establish a horizontal movement for a moving vertical track43. A buffer vehicle 41 traveling on the vertical track 43 can retrievea container from a buffer station 12. The container is transferred fromthe buffer station 12, traveled to the middle row along the verticaltrack 43. The vertical track 43 moves along the horizontal tracks 45Aand 45B to reach the buffer loading station 104/104A. At the bufferloading station 104/104A, the buffer vehicle 41 moves along the verticaltrack 43 to place the container at the buffer loading station 104/104A.Moving container from the buffer loading station 104/104A to the bufferstations 12 can be accomplished by a reversing of direction. From thebuffer loading stations 104/104A, the container can be transfer to theOHT track 105 through the transfer mechanisms 203/203A. This illustratesan exemplary configuration of a buffer mechanism to transfer containersbetween the buffer stations 12 and the buffer loading stations 104/104A.Other mechanisms can also be implemented, for example, a xy tablemechanism or a robotic arm servicing the buffer assembly area.

The two-row configuration of the buffer area provides random access ofthe buffer stations with minimum height. Additional rows would requiredoubling the height to accommodate the back rows. If additional bufferstations are needed, double stack configuration of two-row buffer can beimplemented.

FIG. 10 illustrates an exemplary configuration of the automatic bufferincorporated in the top section of the stocker. The ceiling-based OHTtrack 51 is typically part of the facility, and the stocker 57 havingthe buffer loading OHT station 59 interfacing the OHT track 51. A numberof buffer stations 53 storing containers ready to be transferred to thebuffer loading station 59. Linear guide transfer mechanism 310 drives anOHT vehicle 311 to transport containers from the buffer stations 53 tothe buffer loading station 59. Also shown is the stocker loading station55 for loading the wafers to the stocker and/or to the buffer loadingstation 59. The stocker loading station 55 can receive the containerfrom the OHT station 59, from a MLP station, or from the operator.Multiple stocker loading stations can be installed with optionaltransfer mechanism between them, especially from the OHT loader and theMLP station. Elevator mechanism 315 can transport container in loadingstation 55 to the buffer loading station 59. Robotic mechanism 312 cantransfer substrates or wafers from the container in loading station 55,to be stored bare in compartments 313 within the stocker storage area.Inner robotic 314 can handle bare substrates or wafers within thestorage area.

In exemplary embodiments, the present stocker discloses scalable storagearea with two opposite walls of storage shelves and a middle roboticmechanism servicing the shelves. The length of the wall can be extendedto provide more storage area, together with an extended track for therobot mechanism. Clean room space is expensive, with the width even moreexpensive than the length due to higher cleanliness requirements facingthe front side. Thus exemplary stocker according to the presentinvention provides optimum width with a flexible and scalable length.

The buffer can include a plurality of shelves, each shelf having anupper surface capable of supporting a carrier box. Shelves are designedto have minimum space, thus may be vertically spaced from each other adistance sufficient to support a carrier box, and to allow a robot toenter to transport the carrier box. In one embodiment, the shelves arealigned in a plurality of rows and columns. However the shelves may beprovided in various configurations. In one aspect, a robot is providedwith ability to move in an X-Y Cartesian plane, to access a plurality ofshelves for either buffer or loader.

FIG. 11A illustrates a top view of an exemplary stocker storage area.The storage area comprises 2 opposite walls 63 and 65 of shelves 61.Each wall comprises 2 columns of shelves, serviceable by a roboticmechanism traveling in the center section 62. The robotic mechanismtravels in a track to address different columns of shelves. The roboticmechanism further comprises a vertical movement to address differentrows of shelves stacked in the vertical direction. The robotic mechanismfurther comprises a wafer handling arm to pick up or placing the wafersin the shelves.

FIG. 11B illustrates an exemplary extension of the scalable stocker. Thestocker storage area comprises 3 columns of shelves (instead of 2). Thetrack of the robotic mechanism is also extended to accommodate the newcolumn of shelves. Since the length of the stocker typically extends tothe chase area of the clean room, extension does not occupy morevaluable clean room space.

In exemplary embodiments, each wall of the storage area comprises onelayer of shelves. Thus the width of the stocker can be minimized fortwice the width of the shelves plus the width of the robotic mechanism.In an embodiment, the wafers are stored in close spacing to increase thestorage density. Further, the wafers can be stored vertically forminimum contact at the side edges.

FIG. 12 illustrates a top view of an exemplary stocker utilizing thescalable storage area. The stocker comprises loading stations 71, eitherfor manual loading wafers or for automatic loading using automatic guidevehicle such as OHT track. The configuration shown comprises threeloading stations, with two stations for EFEM and one station for MLP.The EFEM stations allow the operator to load containers to the stocker.The MLP station can transfer container to the EFEM and/or the bufferloading station, located on top of the stocker. Also shown is the OHTtrack 321 for transporting containers from the buffer loading station.

Next to the loading stations 71 is the robotic mechanism 72, fortransferring wafers from the containers within the loading stations 71.A drop station 73 interfacing the robotic mechanism 72 for receiving thewafer, and to change the orientation. The wafers are typically storedhorizontally in the containers (such as FOUP), and then changedorientation to be stored bare and vertically in the compartments 78within the stocker storage area. Drop station can be designed to allowthe wafer to be picked up from the bottom and from the side. Roboticmechanism 75 can receive the wafers from the drop station 73 and storethem in the storage compartments 78. The wafers are preferably stored ina vertical direction with small pitch for high density. Roboticmechanism 75 travels between the compartments 78 and the drop station 73to access the stored wafers.

FIG. 13 illustrates a cross section of an exemplary stocker utilizingthe scalable storage area. The stocker comprises two opposite walls ofstorage shelves 78, storing the wafers in vertical direction. A roboticmechanism 75 can service the shelves, retrieving and placing the wafersto the shelves. OHT station and track are shown on top of the stocker.The stocker possesses flow dynamic to minimize particulatecontamination. Flow across the wafers from the wall passes through thewafer to the center robotic mechanism to the floor, and recirculatesthrough the stocker wall back to the wafer compartment. The flow passesthe wafers only once to ensure cleanliness.

In exemplary embodiments, the present invention discloses a stockerutilizing a combination of automatic buffer and scalable storage area.The exemplary stocker comprises two walls of storage shelves in thestorage area and two rows of buffer stations on the top (or bottom) ofthe stocker. The middle area is to accommodate a robotic mechanism, oneto service the storage shelves, and one to service the buffer stations.

The stocker further comprises a stocker loading station to transferwafers from a container to the storage area. The stocker also comprisesan automatic handling station, such as an OHT loading station, fortransferring the container to the OHT track. There are multiple separatestocker loading station for interfacing with the stocker (EFEM), and anOHT loading station for interfacing with OHT track. There can also betransfer mechanism for moving containers between the stocker loadingstation and the OHT loading station.

The loading station can comprise an EFEM station for handling wafercontainers such as FOUP or SMIF. The loading station can be handled byan operator, thus providing manual handling of the wafer containers.

The loading station can comprise an automatic loading station, such as aMLP (Mobile Launch Platform), designed for accepting containers from anautomatic handling system, such as OHT track, together with a transfermechanism between these stations.

The stocker according to an exemplary embodiment of the presentinvention is designed for storing contamination-sensitive wafer shapearticles such as semiconductor wafers, and reticles. The stockerdesigned is particularly configured for space-saving storage andflexible handling. The stocker, in particular, is well suitable forstoring a large number of 300 mm or larger wafer on a small storagespace under clean conditions.

In an embodiment, the stocker provides that the articles, such assemiconductor wafers, can be stored openly in the clean storage area,together with the robot handling assembly. The robot handling unit thuscan access very fast the individual articles and to pick up and placethem in carrier boxes. The open storage concept can provide high densitywith small footprint storage.

The open storage can be partitioned into compartments to reduce the riskof cross contamination. The compartments can include storage containers,fastened to carrier racks. The stationary of the carrier racks, thestorage containers, the compartments and the articles prevent particlesgenerated from motions, thus substantially reducing the risk ofparticles generated by abrasion, movement and cross contamination airflow.

The storage containers are preferably shaped as an open, box-likecontainer, where the robot handling unit can be adapted optimally toinserting and taking articles out of the storage containers. In apreferred embodiment, the containers are designed for highly densestorage of articles, for example semiconductor wafer with a pitchdistance of less than 5 mm, preferably about 2.5 mm or less. The storagecontainers are arranged in a shelving configuration surrounding therobot handling unit, and preferably approximately circular. The storagecontainers can be arranged in an x-y array, with the shelves openingsfacing a robotic mechanism for transferring the articles. The stationarystocker comprises a plurality of vertically and horizontally spacedshelves each for storing a plurality of articles. The shelves can alsodesigned for storing a plurality of containers where the articles arestored within.

This configuration can provide space-saving arrangement and at the sametime high storage capacity. In addition a very fast accessing of storedarticles can be possible in this configuration.

The robot handling unit includes vertical movement to access thevertical storage containers. The stocker can also include a secondhandling unit for transferring the articles into or from the containers.The stocker can include a blower for producing a continuous clean gasflow toward the containers, and preferably blowing contaminationefficiently downward.

FIGS. 14 and 15 show an exemplary embodiment of a container 18, whichincludes a rear wall 38, a bottom wall 40 and two side panels 42, 44.The rear wall 38 and the bottom wall 40 preferably provide an openingfor releasing clean air flow diagonally across the wafer 20. The airflow between the individual wafers 20 passes through and ensures thatany existing particles and foreign matter are removed diagonallydownward from the container 18.

Within the container 18 four comblike components with splits 50, 52, 54,56 are arranged. The split 50-56 are arranged to hold a wafer by itsdown and back side to permit the removal of the wafer with the robothandling unit 14.

At the upper corner area, there exists a recess 58 to insert a retainer60. The retainer 60 is designed to hold the wafers in place duringmovement of the container 18. Each container 18 may have a handle (notshown), which is connected with the retainer 60, so that a withdrawal ofthe container 18 is only possible if the retainer 60 is inserted in therecess 58.

FIG. 16 shows an exemplary robot handling arm 14 according to thepresent invention, comprising a gripper arm 24, where a wafer 20 a canbe seized at the edges in a vertical position. The grip arm 24 surroundsthe wafer 20 a at its outer circumference in an exemplary C-shaped. Twogrip elements 64 and 66 are arranged at the free ends of the grip arm24. The grip arm 24 surrounds the wafer 20 a along a circular arc“alpha” of more than 180°. The grip elements 64, 66 can hold the wafer20 a therefore without firm wedging and essentially alone due togravity. For the pick up and placement of a wafer 20 a in a carrier box18, the grip elements 64, 66 can be opened. In this figure, only thegrip element 66 is mobile.

The gripper 24 is arranged at the free ends of an arm segment 74. Thearm segment 74 can be swiveling around an axle 76, which lies coaxiallyto a leg of the arm segment 74, where the gripper 24 is located. Thisarrangement makes it possible to take and by a 90° rotation around theaxle 76, bringing a wafer 20 a into a vertical position out of ahorizontal position from the drop station.

The stocker can provide random access to the stored wafer, thus caneliminate the need for a sorter. In particular, the robot handling unit14 is capable of selecting wafers from arbitrary containers 18 into aFOUP. The stocker thus can be integrated with a FOUP front end loader.Due to the vertical storage and the associated high density storagearrangement of the wafers, the stocker can achieve high storage capacitywith small footprint. The storage of the individual wafers in open,separate, box shaped container ensures that cross contamination betweendifferent wafers is difficult despite the open storage configuration.

The stocker storage system is designed so that the storage area is freeof movement components, circuitry, and other contaminant generatingparts. Further, the air flow is filtered before entering the storagearea, and the storage area is designed to have a laminar air flow on thesurfaces of each workpiece, thus ensuring that there is no upstreamcontamination generation source. The clean air flow is then passing theworkpieces toward the robot handling unit, which is located in thecenter of the storage area, downstream of the clean air flow. Thus themovement of the robot handling unit does not contribute to any particlegeneration within the clean air flow path over the workpieces. Othercomponents associated with the operation of the stocker system arelocated external to the storage unit and downstream of the air flow overthe workpieces.

The clean air delivery units can also deliver uniform clean air flowthrough the workpieces and system after being filtered. The storage areais designed to minimize or eliminate non-uniform, turbulent, or deadspace with little or no airflow with symmetric volumes, graduallychanges to the airflow direction, singularly airflow directions, andcontrolled venting. The exhaust venting rate can also be controlled toachieve a positive internal pressure for minimizing contaminationmigration into the storage area.

A series of blowers can circulate clean air horizontally through therack, through the slots of the racks, and over the workpieces. Theblowers can be positioned in the upper or lower areas, and then air isdrawn downwardly or upwardly into an enclosure before travelinghorizontally into the workpieces. The air flow then exits verticallydownward adjacent to the racks. Some of the air can exit near the bottomof storage area through closeable louvers and some of the air can berecirculated back.

The horizontal flow through the workpieces prevents particles fromcoming to rest on the workpieces and the workpiece rack, and thevertically downward air flow removes particles from the stocker storagearea. The horizontal air flow is preferably flowing inward, from theoutside to the center of the stocker storage area. The outside isnormally the enclosure walls, thus is without any particle generation.The robot handling system is located in the center of the stocker, thusis positioned downstream of the air flow from the workpieces, andpreventing particles from damaging the workpieces.

With this flow configuration, the air flow only passes by the workpiecesonce. Thus any particles picked up by the air flow through a workpiecedo not pass through another workpiece to prevent redeposition. The cleanair from the fan and filter unit only passes though a single workpieceand then exits through a bottom of the center robot handling assembly.Moreover, with the robot handling in the center area, the particulatesare most likely generated where the contacts are, such as where therobot arm contacts the workpieces, or where the workpieces contact theslots. The air system through the surfaces of the workpieces blows thegenerated particles away from, and not towards, the workpieces in thestorage area.

1. A buffer assembly interfacing an automatic transport and interfacinga bare substrate stocker, the buffer assembly comprising: a transportbuffer, the transport buffer comprising: one or more buffer stations forstoring one or more containers containing substrates; and a bufferloading station adapted for holding a container; a buffer transfermechanism to transfer a container between the buffer loading station andthe buffer stations; and an interface mechanism adapted for transferringa container between the bare substrate stocker and the transport buffer,wherein the substrates within the container are removed from thecontainer and stored bare in the bare substrate stocker.
 2. A bufferassembly as in claim 1 wherein the interface mechanism is adapted totransfer a container between the bare substrate stocker and the bufferloading station.
 3. A buffer assembly as in claim 1 wherein theinterface mechanism is adapted to transfer a container between the baresubstrate stocker and the buffer stations.
 4. A buffer assembly as inclaim 1 wherein the interface mechanism is adapted to transfer acontainer between the buffer loading station and a stocker loadingstation of the bare substrate stocker.
 5. A buffer assembly as in claim1 further comprising a mechanism to transfer containers between thebuffer loading station and the automatic transport.
 6. A buffer assemblyas in claim 1 wherein the buffer stations are ceiling-based,floor-based, or a combination thereof
 8. A buffer assembly as in claim 1wherein the transport buffer comprises a plurality of buffer loadingstations interfacing with one or more automatic transports.
 9. Animprovement to a bare substrate stocker comprising a buffer assembly forauto transport, the buffer assembly interfacing an automatic transportand interfacing the bare substrate stocker and comprising: a transportbuffer, the transport buffer comprising: one or more buffer stations forstoring one or more containers containing substrates; and a bufferloading station adapted for holding a container; a buffer transfermechanism to transfer a container between the buffer loading station andthe buffer stations; and an interface mechanism adapted for transferringa container between the bare substrate stocker and the transport buffer,wherein the substrates within the container are removed from thecontainer and stored bare in the bare substrate stocker.
 10. Animprovement as in claim 9 further comprising a mechanism to transfer acontainer between the buffer loading station and the automatictransport.
 11. A bare substrate stocker interfacing an automatictransport, the bare substrate stocker comprising: a stocker storage forstoring bare substrates; a stocker loading station adapted for holding acontainer; a stocker loading mechanism adapted for receiving substratesoriginated from the bare substrate stocker to the container and forplacing substrates in the container toward the bare substrate stocker; atransport buffer comprising: one or more buffer stations for storing oneor more containers containing substrates; and a buffer loading stationadapted for holding a container; a buffer transfer mechanism to transfera container between the buffer loading station and the buffer stations;and an interface mechanism adapted for transferring a container betweenthe stocker loading station and the transport buffer.
 12. A stocker asin claim 11 further comprising a drop station interfacing the stockerloading station and the stocker storage, wherein the drop station isadapted to allow the substrate to be picked up at the bottom and at theedge.
 13. A stocker as in claim 11 further comprising an inner roboticmechanism interfacing the drop station and the stocker storage.
 14. Astocker as in claim 11 wherein the substrates are stored in a verticalconfiguration with a pitch less than 2.5 mm in the stocker storage. 15.A stocker as in claim 11 further comprising an algorithm to assemble theneeded substrates to containers to be stored in the buffer stations. 16.A stocker as in claim 11 wherein the interface mechanism is adapted totransfer containers between the stocker loading station and the bufferloading station.
 17. A stocker as in claim 11 further comprising amechanism to transfer containers between the buffer loading station andthe automatic transport.
 18. A stocker as in claim 11 wherein the bufferstations are ceiling-based, floor-based, or a combination thereof
 19. Astocker as in claim 11 wherein the buffer stations are arranged in atwo-row buffer station array with a linear container transfer mechanismin the middle.
 20. A stocker as in claim 11 wherein the transport buffercomprises a plurality of buffer loading stations interfacing with one ormore automatic transports.